Study on The Likelihood Ratio Used to Evaluate the Muscle Tension of Upper Limb Spasm in Hemiplegia Patients

Aim:To evaluate the clinical usability of mechanomyography(MMG)in the evaluation of upper-limb spasticity states of hemiplegia patients with likelihood ratio analysis.Methods:The MMG signals from the 30 hemiplegia patients'biceps and triceps were recorded with three-dimensional wireless accelerometer(Trigno Wireless System,Delsys Inc),when they extended or bent their elbow passively.At the same time,the physiotherapist assessed the MAS(Modified Ashworth Scale)of all the patients who participated in the study and would be divided them into four groups based on the MAS values(MAS0,MAS1,MAS1+and MAS2).The MMG sensors were built with triaxial accelerometers named as X,Y and Z that represent the muscle fibers lengthwise movement,the cross movement and the vertical the muscle moving direction,respectively.The root mean square(RMS)value of the MMG signal was calculated for analysis.Likelihood ratio analysis were used in the study.Results:All of the variables of the X,Y,Z axis of signals of MMG of BB and TB have related with muscle spasticity grading during passive elbow flexion in multinomial logistic regression(P=0.000,P<0.001).The regression coefficient of Y axis signal of MMG of BB is the largest.The 5 variables of the X,Y,Z axis of signals of MMG of BB and X,Y axis of TB have related with Muscle spasticity grading during passive elbow extension in multinomial logistic regression(P=0.000,P<0.001).The regression coefficient ofY axis signal of MMG of BB is the largest in equation and the Y axis signal of MMG of TB is second large.Conclusions:The effect of agonist is more than the antagonist during the MAS assessment,especially the muscle fibers cross movement and the vertical movement by the MMG assessment.

The Influence of Window Length Analysis on the Time and Frequency Domain of Mechanomyographic and Electromyographic Signals of Submaximal Fatiguing Contractions

Mechanomyography (MMG) acquires the oscillatory waves of contracting muscles. Electromyography (EMG) is a tool for monitoring muscle overall electrical activity. During muscle contractions, both techniques can investigate the changes that occur in the muscle properties. EMG and MMG parameters have been used for detecting muscle fatigue with diverse test protocols, sensors and filtering. Depending on the analysis window length (WLA), monitoring physiological events could be compromised due to imprecision in the determination of parameters. Therefore, this study investigated the influence of WLA variation on different MMG and EMG parameters during submaximal isometric contractions monitoring MMG and EMG parameters. Ten male volunteers performed isometric contractions of elbow joint. Triaxial accelerometer-based MMG sensor and EMG electrodes were positioned on the biceps brachii muscle belly. Torque was monitored with a load cell. Volunteers remained seated with hip and elbow joint at angles of 110° and 90°, respectively. The protocol consisted in maintaining torque at 70% of maximum voluntary contraction as long as they could. Parameter data of EMG and the modulus of MMG were determined for four segments of the signal. Statistical analysis consisted of analyses of variance and Fisher’s least square differences post-hoc test. Also, Pearson’s correlation was calculated to determine whether parameters that monitor similar physiological events would have strong correlation. The modulus of MMG mean power frequency (MPF) and the number of crossings in the baseline could detect changes between fresh and fatigued muscle with 1.0 s WLA. MPF and the skewness of the spectrum (μ3), parameters related to the compression of the spectrum, behaved differently when monitored with a triaxial MMG sensor. The EMG results show that for the 1.0 s and 2.0 s WLAs have normalized RMS difference with fatigued muscle and that there was strong correlation between parameters of different domains.

Electromyographic and Mechanomyographic Responses During Isokinetic Leg Extensions in Children Versus Adolescents

Purpose The purpose of this study was to examine peak torque(PT),mean power(MP),electromyographic(EMG)amplitude,mechanomyographic(MMG)amplitude,and neuromuscular efficiency from EMG and MMG amplitude(NME_(EMG)and NME_(MMG),respectively)across the velocity spectrum in children versus adolescents.Methods Seventeen children(n=8 males,n=9 females)and 22 adolescents(n=11 males,n=11 females)participated.Participants completed maximal concentric isokinetic leg extensions at 60,120,180,240 and 300°/s.PT,MP,EMG amplitude,and MMG amplitude were quantified during all muscle actions.NME_(EMG)and NME_(MMG)were quantified by expressing PT relative to EMG and MMG amplitude,respectively,for each muscle action.Results PT,MP,NME_(EMG),and NME_(MMG)were greater for the adolescents than the children collapsed across sex and veloc-ity(P≤0.021).There were no significant differences for EMG amplitude(P≥0.051),while MMG amplitude increased significantly from 60 to 240°/s(P<0.001)then decreased significantly from 240 to 300°/s(P<0.001)for all groups.Conclusion Overall,regardless of velocity,the expression of PT relative to EMG and MMG amplitude(NME_(EMG)and NME_(MMG),respectively),in conjunction with measurements of torque and power production,may provide practitioners a unique method of examining growth and development-related augmentations in neuromuscular function during dynamic movements.

Day to Day Consistency and Inter-subject Variability of Neuromuscular Responses and Performance Fatigability as the Result of Maximal,Bilateral,Dynamic Leg Extensions

Purpose The purpose of the present study was to examine the day-to-day consistency and inter-subject variability of com-posite and individual,neuromuscular and torque patterns of responses as a result of a fatiguing bout of maximal,bilateral,isokinetic leg extension muscle actions.Methods Ten men (Mean ± SD =21.6 ± 2.5 years) completed two testing visits consisting of pretest and posttest maximal voluntary isometric contractions (MVIC) as well as 25 maximal,bilateral,isokinetic (180°/s),leg extension muscle actions.Electromyographic (EMG) and mechanomyographic (MMG) signals were collected from the vastus lateralis and normalized to the MVIC.Performance fatigability was defined as the percent decline in torque between the average of repetitions 1,2,and 3 and repetitions 23,24,and 25.Polynomial regression was used to examine the individual and composite relation-ships between EMG amplitude (AMP),EMG mean power frequency (MPF),MMG AMP,MMG MPF,and torque versus repetitions.Results There was no significant difference (d =0.80;P =0.17) in the performance fatigability between Day 1 (19.3% ± 7.1%)and Day 2 (26.9% ± 11.3%).Polynomial regression indicated substantial inter-subject variability,but high day-to-day consistency.Conclusion The composite EMG AMP,MMG AMP,and MMG MPF patterns of responses demonstrated consistency across days.The composite EMG MPF patterns of responses,however,were not consistent between Day 1 and Day 2.In addition,based on the high inter-subject variability,future studies should present both composite patterns of neuromuscular responses and the patterns of responses on a subject-by-subject basis to make inferences regarding fatigue-induced changes in motor unit activation strategies.

Sex-Related Differences in Performance Fatigability Independent of Blood Flow Following a Sustained Muscle Action at a Low Perceptual Intensity

The purpose of this investigation was to use the RPE clamp protocol to examine sex-related differences in performance fati-gability and neuromuscular responses as the result of a sustained isometric leg extension muscle action anchored to RPE=2.Twenty adults(10 men,10 women)performed sustained muscle actions at RPE=2 for 5-min.Maximal voluntary isometric contractions(MVIC)were performed prior to and following the sustained muscle actions.Neuromuscular(electromyographic and mechanomyographic)parameters and force were recorded,and the values were normalized to respective MVICs and cal-culated every 5%across the 5-min work bout.Femoral artery blood flow(FABF)was assessed at pretest,immediately posttest,and 5-min posttest.Polynomial regression was used to define the individual and composite normalized neuromuscular and force versus time relationships during the sustained muscle action.Mixed factorial ANOVAs were used to examine differences in performance fatigability and blood flow.For performance fatigability,the men(62.4±14.4 kg-43.1±11.5 kg)exhibited a significantly(P<0.05)greater decrease pretest to posttest in MVIC than the women(44.1±4.8 kg vs.38.1±6.1 kg).There were different fatigue-induced neuromuscular patterns of responses between the men and women across time.For blood flow responses,however,there was no sex-related difference,but pretest(283.3±70.8 mL/min)was significantly(P<0.05)less than immediately posttest(424.5±133.5 mL/min)and 5-min posttest(324.4±78.3 mL/min).Thus,men demonstrated a greater degree of performance fatigability than the women,which was independent of differences in FABF.Factors such as the neuromuscular system and muscle morphology likely contributed to the difference in performance fatigability.

Caffeine Increases Rate of Torque Development Without Affecting Maximal Torque

Purpose The purpose of this study was to examine the effects of caffeine on peak torque(PT),rate of torque development(RTD),and muscle activation in college-age men.Methods Fifteen men(23.3±2.2 years,177.6±8.7 cm,90.3±19.1 kg)volunteered to participate in this study.During each of two test sessions,maximal leg extension PT and RTD were determined and electromyographic(EMG)and mechano-myographic(MMG)signals were collected to examine electrical and mechanical aspects of muscle activation,respectively.Participants also performed the Wingate Anaerobic Test(WAnT)for the determination of peak power(PP),mean power(MP),and fatigue percentage(FP).For the first test session,participants were randomly assigned to ingest either a caffein-ated drink(6 mg/kg)or a placebo 1 h prior to testing.The second test session was identical to the first,but the drink not previously administered was ingested prior to testing.Results The results indicated there were no significant effects of caffeine on PT,PP,MP,FP,or EMG and MMG measures.However,RTD was positively affected by caffeine(856.4±246.4 Nm/s)compared to the placebo condition(710.9±267.9 Nm/s).Conclusions These results suggest that caffeine can be an effective aid for sport activities requiring maximal rates of force or torque development during very short time periods.